A. UNDERSTANDING THE DEFINITION OF
PHOTOSYNTHESIS
Photosynthesis is the process of making high-energy
foods molecule from simpler components, carried out by autotrophic plants
(plants that can make a food in itself). Photosynthetic, word “photon” comes
from the word meaning "light" and “synthesis”, which means "composer",
so photosynthesis is also defined by biochemical processes carried out by
plants to produce energy (nutrition) by utilizing light energy.
The leaves are the main components in plants that
plays a role in photosynthesis, the leaves has chlorophyll (the green
substance), this chlorophyll will absorbs solar energy that can be harnessed to
produce energy (nutrition).
Photosynthesis is very important for all organic life
on earth. Beside producing energy, photosynthesis process will also produce
oxygen for human life and other living creatures.
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| PHOTOSYNTHESIS PROCESS |
B. THE FUNCTION OF PHOTOSYNTHESIS
The main function of photosynthesis is to produce
glucose as the main energy source for the plant, in the presence of glucose
will be formed energy sources like fat and protein as well. These substances
will be a source of food for humans and animals, therefore the process of
photosynthesis is very important in our lives.
Photosynthesis process can clear the air. The air is
cleaned by absorbed the carbon dioxide and produces oxygen. So this is why
planting trees can clean up the environment.
The ability of photosynthesis in plants during their
lifetime will make the rest of the plant body is buried in the ground when they
die. In a long time, Heaps of these plants will make it into coal, a raw
material and an energy source in modern life.
C. THE PROCESS OF PHOTOSYNTHESIS
Before starting the explanation, please note the
chart below first.
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| PHOTOSYNTHESIS DIAGRAM |
Based on the chart are then briefly the process of
photosynthesis can be explained :
In the process of photosynthesis there are four
ingredients that must be held :
- Carbon dioxide
- Water
- Sunlight
- chlorophyll
Carbon dioxide will be taken by Stomata (mouth leaves) on the leaves of plants from the air, then the water is taken through plant roots and transported to the plant-carrying component,, then sunlight will be taken in the form of energy by chlorophyll (the green substance). All these processes will take place to form a reaction and produce oxygen and glucose.
Once the glucose contained in plants, these nutrients will be converted into fat, protein, and other nutrients.
Actually, The photosynthesis reaction is much more
complex, what we explained above is the simplest way to understand
Photosynthesis process.
D. STAGES OF PHOTOSYNTHESIS REACTION
The process of photosynthesis that occurs in
chloroplasts consists of two reactions; the light reaction and a dark reaction.
1. Light
Reaction
It called light reaction because the reaction process
requires sunlight. This reaction occurs in one of the empty space of the
chloroplast, called the thylakoid membrane. In the light reaction, chlorophyll
absorbs light from the sun, the energy gained from solar light is used to split
water molecules into oxygen and hydrogen molecules. This reaction is called
photolysis, and can be described by the following reaction.
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| LIGHT AND DARK REACTION OF PHOTOSYNTHESIS |
2. Reaction
Dark
As the name implies dark reaction is a reaction that
is not dependent on light. The main function of the dark reactions is the
conversion of carbon dioxide (CO2) into glucose. This dark reactions occur in
the chloroplast stroma. Dark reaction will occur only after the light reaction
and a dark reaction process is more complex than the light reaction.
E. FACTORS AFFECTING PHOTOSYNTHESIS
1. Internal
Factors
internal factor is derived from the plant itself. It
means each of a different plant types, although living in the same
circumstances will have different photosynthetic reaction, maybe we can say
that internal factors are heredity (offspring).
There are some species that can not form chlorophyll
(albino) so it will greatly affect their photosynthetic reaction.
2. External
Factors
a. Water and
mineral content of the soil
As we have explained earlier, water is one of the raw
materials used for the photosynthesis reaction so if there is more water in the
soil, the better the reaction. Because Photosynthesis is very dependent on the
absorption of water by the plant roots.
b.
temperatures
Photosynthesis is a reaction that depends on the
enzyme, while the action of the enzyme is affected by temperature. Enzymes can
not work at temperatures below 5 degrees Celsius and above 50 degrees Celsius,
if the temperature does not match, then photosynthesis will not happen. The
best temperature for photosynthesis is between 28-30 degrees Celsius.
c. The CO2 in
the air
CO2 in the air is around 0.03 percent, the more CO2 it
get the better reactions would be.
d. O2
The low content of O2 in the air and in the soil will
inhibit plant respiration. Disturbance of this respiration will also inhibit
the photosynthesis process by the plants.
